Petroleum coke is a fuel that has high heating value and low volatility but has a disadvantage in that it contains a high sulfur content. Such high sulfur content fuels must be combusted in the presence of sulfur dioxide acceptors for sulfur dioxide resulting from the combustion or the resultant combustion gases must be contacted with a sulfur dioxide acceptor so that objectionable amounts of sulfur dioxide are not released to the atmosphere following combustion. An especially useful combustion process for petroleum coke involves the use of a fluidized bed boiler where limestone is injected as a sorbent for sulfur dioxide. At the combustion temperatures, the limestone (CaCO.sub.3) is calcined to form lime and carbon dioxide (CaO+CO.sub.2) with the lime reacting with sulfur dioxide in the combustion gas to form anhydrous calcium sulfate (CaSO.sub.4). The resultant combustion ashes are in two forms, a bed ash, or solids resulting from the combustion that are collected in the boiler, and a cyclone ash, or gas-borne solids that are removed from the combustion ashes in a cyclone or other separator prior to discharge of the combustion gas to the atmosphere.
The combustion bed ash and cyclone ash from a petroleum coke-fired fluidized bed combustion (PCFBC) are composed of primarily calcium oxide and anhydrous calcium sulfate with small amounts of magnesium oxide, silicon dioxide, iron oxide and aluminum oxide and have a much higher free lime, or quicklime, (CaO) content than a coal fired FBC. If water is added to the hot, dry, combustion bed ash and cyclone ash to place it in condition for transfer to a disposal site, an enormous amount of heat and vapor are created which, in an enclosed area, causes an unsafe situation. Ash that cannot be used in a dry state, shipped directly from storage, must be trucked to a land storage site in a moist condition in order to control fugitive dust from wind or truck traffic. The petroleum coke-fired fluidized bed combustion ash has a large demand for water in order to be able to maintain a residual moisture content in a land storage site. Also, to water-condition the ash so that it can be used as a road construction material, a large amount of water must be added in a controlled manner. The use of ash conditioners, located at the confined and high traffic area of a power plant, to hydrate the high quicklime containing material, is impractical and unsafe due to the dangerously high heat of hydration and steam vapors, which result in visibility problems. Excessive water addition also creates a dangerous situation where water spillage from open transfer dump trucks allows wet ash to collect on roads.